Corrugator machines have been long and widely used in the manufacture of laminated corrugated board materials. Such a machine is described in Wicker U.S. Pat. No. 3,368,933 (1968) which shows in detail a corrugator combiner machine which continuously combines an inside corrugated sheet with an upper and a lower flat liner sheet using a liquid adhesive, typically an aqueous solution of sodium silicate or starch. These three sheets, treated with adhesive, are brought together and pressed by one or more endless belts which carry them on to a series of heated plates to be dried. The heat from the plates is conducted directly to the assembled corrugated web to dry it while being held down by the endless belts.
Other designs for corrugated board-making machinery are shown in patents to Lawton U.S. Pat. No. 4,042,446 (1977); Bennett et al., U.S. Pat. No. 4,935,082 (1990); Marschke, U.S. Pat. No. 5,561,918 (1996); Teschner U.S. Pat. No. 5,539,997 (1996); Knorr et al. U.S. Pat. No. 5,632,850 (1997); and Marschke et al. U.S. Pat. No. 6,074,520 (2000). Some of these machines use endless corrugator belts while others do not. The present invention is particularly adapted for use with machines in which an endless corrugator belt is employed.
In addition to their drying function, the endless belts also serve to frictionally engage and transport the web past the heated plates and into a cooling section of the combiner machine. Features which are necessary or desirable for such corrugator belts include qualities of strength, heat resistance, moisture resistance, and being relatively porous so as to permit the transmission and escape of water vapor from the drying corrugated product. Such belts must also be wear-resistant, particularly at their outer edges. They further must be rigid in the cross-machine direction so as not to distort while carrying the finished corrugated product along its intended path.
In response to these needs, several corrugator belts have been developed. Typical examples are described in patents to Romanski et al. U.S. Pat. No. 4,403,632 (1983); Birzele U.S. Pat. No. 5,785,621 (1998); Lanthier U.S. Pat. No. 6,276,420 B1 (2001); and Billings et al. U.S. Pat. No. 6,470,944 B1 (2002).
The process of manufacturing continuous sheets of corrugated board is inherently dusty and dirty. The corrugator belts used on most such machines typically become fouled with a stubborn, deeply ingrained coating of paper lint, adhesive particles, and debris of all kinds. Regular cleaning is therefore required. Because the corrugator web is typically constructed of a porous, moisture-resistant polymer, the cleaning process is typically very much like that used for the cleaning of synthetic carpets in homes and businesses. A heated spray of water-based detergent is forcibly directed at and into the body of the web, sometimes together with mechanical scrubbing or other agitation of the cleaning solution, followed by a vacuum cleaning process to remove as much of the suspended or dissolved debris as possible, leaving the web clean and relatively dry, and ready for re-use. Such a cleaning process requires that the corrugator machine be stopped so that an operator can climb on top of the web (being the paper-contacting surface on its return path) to perform the necessary cleaning operations. The entire machine must be shut down to perform this operation, with a consequent loss of production. Production managers must carefully coordinate their operations to permit these periodic cleanings without interrupting the operation of the entire line and temporarily idling the entire operating staff. When an unforeseen condition requires an unscheduled cleaning, production planning and staffing schedules can be seriously disrupted. Further, there are physical dangers for the cleaning operator, who at present is required to climb atop the web and walk upon it while applying the cleaning solution, agitating it to loosen and remove dirt and debris, and vacuuming up the residue.
The cleaning of endless belts of various kinds has been the subject of certain prior art patents, but the solutions there described have little applicability to solving the problems presented by the in-place cleaning of a corrugator web belt, particularly while the corrugator machine is in continuous operation. For instance, Schaefer et al. U.S. Pat. No. 6,601,692 B2 (2003) discloses a moving brush in the form of an endless loop carried by a track aligned transversely to a moving bulk material conveyor belt. The brush cleans the belt of any adhering remaining material which might cause damage to the belt as it continues along its recirculating path.
Bright U.S. Pat. No. 4,365,706 (1982) discloses another conveyor belt cleaning device in which a fixed scraper member is positioned transversely across the belt to physically scrape off any adhering material. The scraper is resiliently urged against the face of the belt, but has no provision for applying a cleaning solution or vacuuming up the residue. Similar belt cleaning devices are disclosed by Rappen U.S. Pat. No. 5,114,000 (1992) and Tenzer U.S. Pat. No. 6,349,816 B1 (2002).
Franzoni et al. U.S. Pat. No. 6,533,102 B2 (2003) discloses a conveyor belt cleaner in which one or more cleaning rollers cooperate to form a solvent-retaining receptacle, which serve to clean the belt by rotating in a direction opposite to the direction of belt movement. No physical scrubbing action or vacuum removal of residue is disclosed or suggested. Chupin et al. U.S. Pat. No. 4,918,778 (1990) discloses a similar solvent-dipping device in which the belt is directed into a solvent dip tank with a spray arrangement coupled with a squeezer roller, with the belt being dipped a second time before returning to its normal path. No mechanical agitation or vacuum removal of residual solvent is shown or suggested, making it impractical for use with a corrugator machine.
Straub U.S. Pat. No. 6,135,267 (2000) discloses a spray device for cleaning a continuous transport screen or belt as used in the manufacture of paper, felt and the like. One or more fixed spray units are positioned to discharge a spray of cleaning fluid onto the opening (exit side) nip of a drive roller, while a surrounding suction chamber draws the contaminated cleaning fluid back for recycling or disposal. However, the spray nozzles are fixed and no mention is made of using a forceful stream for dislodging and removing any adhering particles or debris. The device is intended for use with a relatively porous belt and relies on the cleaning agent penetrating to the other side of the belt, such that both sides are cleaned simultaneously. The suction chamber of the device must therefore be positioned at the nip of the roller to strengthen the effect of the vacuum as it exits the nip (col. 2, lines 16–18). Another machine for a like purpose is disclosed by Kotitschke U.S. Pat. No. 5,517,714 (1996) in which a continuous spray is directed onto and through the web, with the residue being collected in a trough on the other side. Neither these nor any of the other prior art patents described herein could find practical application in a corrugator machine for cleaning a continuously moving corrugator belt.